川西高寒山区沥青路面层间特性及其对结构疲劳性能影响机理

The Western Sichuan plateau-cold region with special natural conditions, which containing complex terrain, low temperature, abundant rainfall, large elevation changing, and large temperature changing. In this region, the contact characteristics have significant effects on asphalt pavement structural behavior. Based on the early development of ten years, the contact characteristics of asphalt pavement in eastern margin of Tibetan Plateau of Western Sichuan plateau-cold region and its effect on the structure fatigue failure mechanism will be studied in this project. Normal Direct Shearing Test, Tangential Pull-out Test and Skew Shearing Test will be used to study the vertical-horizontal effect on the contact interface between asphalt pavement layers, and to determine the related parameters and models. On the basis of fatigue properties and fundamental parameters of materials for each layers of asphalt pavement, the fatigue behaviors of pavement structures by comprehensive actions of large temperature changing and vehicle loading will be studied by finite element analysis (FEA) with contact mechanics and fracture mechanics. The emphasis of which is the mechanics effect and the fatigue failure effect between pavement layers, and to quantitatively describe the internal relation between characteristics of fatigue and contact using systemized evaluation indices. Summarizing the results of the materials tests, theoretical analysis and full-scale model tests, a comprehensive fatigue model for Material-Structural correlation of asphalt pavement by comprehensive actions of temperature and vehicle loading with considering contact characteristics will be established by introducing impact factor of contact fatigue in layers and by fitting the related parameters. The outcomes of this research can be taken as the theoretical basis and technical support for the structure and material design of asphalt pavement in Western Sichuan plateau-cold region.

川西山区位于青藏高原东缘，地形险峻，降雨充沛，其高寒低温运营环境严重影响沥青路面层间特性，并进而制约路面使用性能与寿命。本项目在近十年的前期实地调研和研究基础上，开展川西高寒山区-青藏高原东缘进藏高等级公路沥青路面层间特性及其对结构疲劳性能影响机理研究。通过"法-直剪"、"切-拉拔"以及斜剪等试验，研究层间界面的法-切向粘滞剪切效应，确定其力学参数与模型；采用大尺寸复合梁弯曲疲劳试验方法，确定沥青面层材料疲劳特性；采用断裂力学有限元方法，以及足尺疲劳模型试验，研究大温差与车辆荷载综合作用下层间力学效应对路面疲劳性能的影响机理，探明结构疲劳与层间特性的内在联系；综合材料试验、理论分析与模型试验结果，提炼层间状态疲劳影响因子，寻求材料疲劳与结构疲劳的关联性，构建基于层间特性的荷载与温度综合作用下的沥青面层疲劳性能评价模型。项目研究成果为川西高寒山区沥青路面结构与材料设计提供理论依据和技术支撑。

本研究针对川西高寒山区特殊自然条件，采用室内试验和数值模拟相结合的方法，对沥青路面层间特性及其对路面结构疲劳性能影响机理开展研究，主要研究成果包括：1）研发了沥青混合料层间抗剪强度辅助测量装置，应用该装置进行了层间粘结剪切试验，分析了层间界面法-切向粘滞剪切行为，构建了低温、常温、高温三种温度条件下沥青层层间粘结剪切力学模型；2）研发了基于四点弯曲梁法的沥青混合料层间剪切强度测试装置，进行了界面剪切疲劳试验，构建了层间剪切疲劳模型；3）通过层间直接剪切试验、含层间界面复合小梁的四点弯曲疲劳试验，研究了层间上下层混合料组合、界面水、层间污染（尘污、油污）等因素对沥青层层间粘结能力、复合试件疲劳性能的影响，构建了基于疲劳现象学的复合小梁疲劳寿命方程；4）针对高寒大温差地区季节时温变化特点，考虑沥青混凝土的时温粘弹性性质，通过数值模拟计算分析，确定了沥青路面结构在不同轴重、动载频率、层间状态、温度时刻作用下的动静力学特性与疲劳寿命特点；5）基于断裂力学及有限元数值模拟方法，分析了移动荷载作用下不同双裂纹间距、不同反射裂纹深度对面层Top-Down（纵向）、基层反射（横向）裂纹应力强度因子的影响，明晰了其开裂扩展特性，评估了其断裂疲劳寿命；6）针对BRT公交车进站制动状态下沥青铺装结构受力特征，采用有限元数值模拟方法，研究了不同铺装结构在不同工况的刹车减速状态下桥面的动力行为特性，解释了其作用机理，提出了加强层间粘结的建议；7）采用正交试验方法，进行了不同温度条件下的沥青铺装层层间粘结材料的直剪、斜剪、拉拔等试验，确定了各粘结材料的性能特点，提出了基于层间疲劳耐久性的材料优选建议，结合层间接触状态对铺装结构动静力学响应分析结果，提出了桥面沥青铺装结构优化建议。研究成果对深入认识层间法-切向力综合作用行为、合理设计高寒山区沥青铺面结构与材料、科学评价路面疲劳性能等均具有重要意义。